|
Plant Disease Epidemiology
Plant disease epidemiology is the study of disease in plant populations. Much like diseases of humans and other animals, plant diseases occur due to pathogens such as bacteria, viruses, fungi, oomycetes, nematodes, phytoplasmas, protozoa, and parasitic plants. Plant disease epidemiologists strive for an understanding of the cause and effects of disease and develop strategies to intervene in situations where crop losses may occur. Destructive and non-destructive methods are used to detect diseases in plants. Additionally, understanding the responses of the immune system in plants will further benefit and limit the loss of crops. Typically successful intervention will lead to a low enough level of disease to be acceptable, depending upon the value of the crop. Plant disease epidemiology is often looked at from a multi-disciplinary approach, requiring biological, statistical, agronomic and ecological perspectives. Biology is necessary for understanding the pathogen and its life cycle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disease
A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that are associated with specific signs and symptoms. A disease may be caused by external factors such as pathogens or by internal dysfunctions. For example, internal dysfunctions of the immune system can produce a variety of different diseases, including various forms of immunodeficiency, hypersensitivity, allergies and autoimmune disorders. In humans, ''disease'' is often used more broadly to refer to any condition that causes pain, dysfunction, distress, social problems, or death to the person affected, or similar problems for those in contact with the person. In this broader sense, it sometimes includes injuries, disabilities, disorders, syndromes, infections, isolated symptoms, deviant behaviors, and atypical variations of structur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dutch Elm Disease
Dutch elm disease (DED) is caused by a member of the sac fungi (Ascomycota) affecting elm trees, and is spread by elm bark beetles. Although believed to be originally native to Asia, the disease was accidentally introduced into Americas, America, Europe, and New Zealand. In these regions it has devastated native populations of elms that did not have resistance to the disease. The name "Dutch elm disease" refers to its identification in 1921 and later in the Netherlands by Dutch phytopathologists Marie Beatrice Schol-Schwarz, Bea Schwarz and Christine Buisman, who both worked with professor Johanna Westerdijk. The disease affects species in the genera ''Ulmus'' and ''Zelkova''; therefore it is not specific to the Ulmus × hollandica, Dutch elm hybrid. Overview Dutch elm disease (DED) is caused by ascomycete microfungi. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Powdery Mildew
Powdery mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of ascomycete fungi in the order Erysiphales. Powdery mildew is one of the easier plant diseases to identify, as its symptoms are quite distinctive. Infected plants display white powdery spots on the leaves and stems. The lower leaves are the most affected, but the mildew can appear on any above-ground part of the plant. As the disease progresses, the spots get larger and denser as large numbers of asexual spores are formed, and the mildew may spread up and down the length of the plant. Powdery mildew grows well in environments with high humidity and moderate temperatures. Greenhouses provide an ideal moist, temperate environment for the spread of the disease. This causes harm to agricultural and horticultural practices where powdery mildew may thrive in a greenhouse setting. In an agricultural or horticultural setting, the pathogen can be controlle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flax
Flax, also known as common flax or linseed, is a flowering plant, ''Linum usitatissimum'', in the family Linaceae. It is cultivated as a food and fiber crop in regions of the world with temperate climates. Textiles made from flax are known in Western countries as linen and are traditionally used for bed sheets, underclothes, and table linen. Its oil is known as linseed oil. In addition to referring to the plant, the word "flax" may refer to the unspun fibers of the flax plant. The plant species is known only as a cultivated plant and appears to have been domesticated just once from the wild species ''Linum bienne'', called pale flax. The plants called "flax" in New Zealand are, by contrast, members of the genus ''Phormium''. Description Several other species in the genus ''Linum'' are similar in appearance to ''L. usitatissimum'', cultivated flax, including some that have similar blue flowers, and others with white, yellow, or red flowers. Some of these are perennial pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fusarium Wilt
Fusarium wilt is a common vascular wilt fungal disease, exhibiting symptoms similar to Verticillium wilt. This disease has been investigated extensively since the early years of this century. The pathogen that causes Fusarium wilt is ''Fusarium oxysporum'' (''F. oxysporum'').Snyder, W.C. and Hansen, H.N. 1940. The species concept in Fusarium. Am. J. Bot. 27:64-67. The species is further divided into ''formae speciales'' based on host plant. Hosts and symptoms The fungal pathogen ''Fusarium oxysporum'' affects a wide variety of hosts of any age. Tomato, tobacco, legumes, cucurbits, sweet potatoes and banana are a few of the most susceptible plants, but it also infects other herbaceous plants. ''F. oxysporum'' generally produces symptoms such as wilting, chlorosis, necrosis, premature leaf drop, browning of the vascular system, stunting and damping-off. The most important of these is vascular wilt. Fusarium wilt starts out looking like vein clearing on the younger leaves and droo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Death Rate
Mortality rate, or death rate, is a measure of the number of deaths (in general, or due to a specific cause) in a particular population, scaled to the size of that population, per unit of time. Mortality rate is typically expressed in units of deaths per 1,000 individuals per year; thus, a mortality rate of 9.5 (out of 1,000) in a population of 1,000 would mean 9.5 deaths per year in that entire population, or 0.95% out of the total. It is distinct from "morbidity", which is either the prevalence or incidence of a disease, and also from the incidence rate (the number of newly appearing cases of the disease per unit of time). An important specific mortality rate measure is the crude death rate, which looks at mortality from all causes in a given time interval for a given population. , for instance, the CIA estimates that the crude death rate globally will be 7.7 deaths per 1,000 people in a population per year. In a generic form, mortality rates can be seen as calculated using (d/ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birth Rate
The birth rate for a given period is the total number of live human births per 1,000 population divided by the length of the period in years. The number of live births is normally taken from a universal registration system for births; population counts from a census, and estimation through specialized demographic techniques. The birth rate (along with mortality and migration rates) is used to calculate population growth. The estimated average population may be taken as the mid-year population. Natality is another term used interchangeably with 'birth rate'. When the crude death rate is subtracted from the crude birth rate (CBR), the result is the rate of natural increase (RNI). This is equal to the rate of population change (excluding migration). The total (crude) birth rate (which includes all births)—typically indicated as births per 1,000 population—is distinguished from a set of age-specific rates (the number of births per 1,000 persons, or more usually 1,000 femal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spore
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, fungi and protozoa. Bacterial spores are not part of a sexual cycle, but are resistant structures used for survival under unfavourable conditions. Myxozoan spores release amoeboid infectious germs ("amoebulae") into their hosts for parasitic infection, but also reproduce within the hosts through the pairing of two nuclei within the plasmodium, which develops from the amoebula. In plants, spores are usually haploid and unicellular and are produced by meiosis in the sporangium of a diploid sporophyte. Under favourable conditions the spore can develop into a new organism using mitotic division, producing a multicellular gametophyte, which eventually goes on to produce gametes. Two gametes fuse to form a zygote which develops into a new s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grey Leaf Spot
Grey leaf spot (GLS) is a foliar fungal disease that affects maize, also known as corn. GLS is considered one of the most significant yield-limiting diseases of corn worldwide. There are two fungal pathogens that cause GLS: ''Cercospora zeae-maydis'' and '' Cercospora zeina''.Ward, J. M. J., E. L. Stromberg, D. C. Nowell, and F.W. Nutter, Jr. 1999. Gray leaf spot: A disease of global importance in maize production. ''Plant Disease'' 83: 884-895 Symptoms seen on corn include leaf lesions, discoloration ( chlorosis), and foliar blight. Distinct symptoms of GLS are rectangular, brown to gray necrotic lesions that run parallel to the leaf, spanning the spaces between the secondary leaf veins. The fungus survives in the debris of topsoil and infects healthy crops via asexual spores called conidia. Environmental conditions that best suit infection and growth include moist, humid, and warm climates. Poor airflow, low sunlight, overcrowding, improper soil nutrient and irrigation manageme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time
Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, and to quantify rates of change of quantities in material reality or in the conscious experience. Time is often referred to as a fourth dimension, along with three spatial dimensions. Time has long been an important subject of study in religion, philosophy, and science, but defining it in a manner applicable to all fields without circularity has consistently eluded scholars. Nevertheless, diverse fields such as business, industry, sports, the sciences, and the performing arts all incorporate some notion of time into their respective measuring systems. 108 pages. Time in physics is operationally defined as "what a clock reads". The physical nature of time is addre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Society Of Agronomy
The American Society of Agronomy (ASA) is a scientific and professional society of agronomists and scientists of related disciplines, principally in the United States but with many non-U.S. members as well. About It was founded December 13, 1907 with the objective of 'the increase and dissemination of knowledge concerning soils, crops, and the conditions affecting them. One of its founding members was Charles Piper, who would become its president in 1914. The first president was Mark A. Carleton and the first annual meeting was held in Washington, D.C., in 1908. Two daughter societies were subsequently formed, the Soil Science Society of America (SSSA) and the Crop Science Society of America (CSSA). These 3 societies, the Agricultural Tri-Societies, each have their own boards of directors, their own bylaws, and their own membership rosters. The societies each minimize their expenses by sharing an office and staff (who job-share between the 3 societies), and their annual meeting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agronomy Journal
''Agronomy Journal'' is a peer-reviewed scientific journal published by American Society of Agronomy. The journal publishes articles related to soil science, crop science, agroclimatology and agronomic modeling, production agriculture, and software. About This journal was founded in 1908 under the name ''Journal of the American Society of Agronomy,'' but the name was changed January 1949 to ''Agronomy Journa''l after a vote of the members. In its over one hundred years of existence, it has featured more than 30,290 authors, who have published more than 15,232 articles. The current editor-in-chief is Silvia Pampana in the Department of Agriculture, Food and Environment (DAFE), at Università di Pisa. According to the ''Journal Citation Reports'', the journal has a 2020 impact factor of 2.240.{{Cite book, title= 2020 Journal Citation Reports, publisher=Thomson Reuters Thomson Reuters Corporation ( ) is a Canadian multinational media conglomerate. The company was founde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
